Treatment of hydrocarbon oils



Mach 7, 1.939. J. w. MccAr-FRY TREATMENT oF HYDRocARBoN oILs l original Filed Jan. e, 1932 {Illlllll fbfllall Patented Mar. 79 1.9-3.9

UNITED f rrr ornrnnocsanou ons John Warren cCaffrey, Chicago, Ill., assignor,

' by mesne ents, to Universal Oil Prodnots Comny Chicago, Ill.. a corporation of Deia.

Application .i c, less. serai No. 584,927

Y ."wnam.

This invention relates to the treatment of hydrocarbon-oils and more particularly refers to a process and apparatus for the maximum production of hydrocarbon oils boiling within the motor 5 fuel 'range and possessing relatively high anti-' the complete process, under highly super-atmet pheric pressure for the production of an hydrogenated end point distillate within the motor fuel boiling range. The processessentially in- 2o cludes the commingling of these cracked and hydrogenated gasoline products and their reconversion in a third-system underl independently controlled conditions for the formation of a reformed gasoline o! high antiknockvalue and .25 other -desirable qualities.

A feature of the invention is the utilization of the noncondensable gases produced inthe diil'ernt stages of the complete process as a source of supply of hydrogen. Althoughl in the molecular state lthe appreciable amount of hydrogen produced in the process assists the hydrogenating reactions which o! course are promoted and primarily influenced by the active or nascent hydrogen introduced to the process under elevated temperatures and pressures. The presence oi' the excess supply of'hydrogen induencae the hydrogenating reaction similarly as excess of any reagent inuences a chemical reaction from ergui-- llbrlum towards completion in any indicated di- 140 muon. 1 Illustration of the advantage of' this feature ci' recycling gases to the hydrogenating operation will appear later in this application.

In' a more speciiicfembodiment, the invention' contemplates subjecting raw oil stock to conversion conditionsin a coil and chamber, withdrawing all of the conversion .products out of' the bottom of the chamber and discharging them under substantially reduced pressure into a vaporizer, i'ractionating, condensing and collectn ing the desirable portion oi' the vapors while returning the insumciently converted products separated out in the fractionator to the cracking coil for further conversion, withdrawing the flashdistilled residual oils from/the vaporizer and suby u jecting them. in the presence ofnascent hydronewed February 13, 1937 (ci. 19a- 62) gen, to elevated temperatures and highly superatmospheric pressure in an hydrogenation zone, fractional-ing, condensing and collecting the resulting vapors under greatly reduced pressure, while returning theinsumciently convertedprods ucts separated out in the fractlonator to the hydrogehating coil for further conversion, commingling the cracked and hydrogenated distil-x lates and subjecting a selected mixture to independently controlled conversion'condltions in a lo third system, fractionatlng, condensing and co1- lecting the desirable vapors while returning reux condensate from the fractionator to either the cracking zone or the hydrogenating zone, or dividing it between the two zones and utilizing ald selected .portion of the xed gases produced in the three steps of the operation as a supply of hydrogen-containing gases to assist the work of l the nascent hydrogen introduced to the hydrov gena'tion zone. 20

In another embodiment residual oils from any cracking process whether employing the feature of withdrawing all reaction products out of the` bottom of the reaction chamber and discharging' the same to a zone of reduced pressure, or so 25 treating only the non-vaporized oils from the reaction chamber, or producing residuum without any pressure reduction thereon, may be subjected to treatment with nascent hydrogen in` any conjointly operated hydrogenating process, m and the cracked'and hydrogenated .distillates obtained 'from the conjolntly operated processes reformed ina third system as described in the previous embodiment. Thus the quality and quantity 'of the residuum subjected to hydro- 35 genation is in a'degree controllable and by that very fact the relative quality and quantities of the cracked and hydrogenated dlstlllates are controllable within limitations.

In still another `embodiment the cracked and 40 hydrogenated distillates maybe blended in any desirable proportions in order t obtain useful and valuable blends of gasoline without subjecting the-mixture to the reforming step described v in this process. Thus' the hydrogenated distillate, 45

generally of higher'quality than'the cracked distillate produced in the conjointly operated system, may be blended with the cracked distillate much the same as cracked and straight run gasolines are blended together in order to improve 50,

'the motor fuel qualities of the straight run. gasoj line. Similarly this blending of hydrogenated and cracked gasolines will improve lvthe motor fuel qualities of the cracked gasoline, in any cases to such a degree that the blended product will have 5o i our present day premium motor fuels.

A more complete and detailed knowledge of the operation of the various steps in the process covered by this invention can be had from a description of the preferred operation of the process in connection with the accompanying drawing.

Raw oil charging stock is introduced to the systemthrough valve I and line 2 and directed by means of pump 3 through line 4 'and valve 5 to the upper section of fractionator 6,. wherein it comes into direct contact with the hot vapors therein, and assists in their fractionation, while being itself preheated and stripped of any light low boiling fractions. The non-vaporized raw oil, together with reflux condensate from the fractionator, is withdrawn through line 1 and valve 8 and directed by means of pump 9 through valve I8 and line II to the first heating coil I2 suitably disposed within any type of appropriate furnace A. If preferred, any portion or all of the raw oil charging stock may be pumped directly through line`|3 and valve I4 and line Il to heating coil I2. The charged materials are subjected to conversion conditions and discharged from the furnace through line I5 and valve I6 into chamber I1, wherein sumcient time element is afforded for the completion of conversion reactions. .All of the conversion products are withdrawn from the bottom of the chamber through line I8 and discharged under reduced pressure through pressure reducing valve I9 into vaporizer 28, wherein the separation of the liquid and vaporous products occurs.

The .vaporous products pass through line 2| and valve 22 intothe lower section of fractionator 6, wherein they are fractionated by means of direct contact with that portion of the raw oil charging stock delivered overhead and any other refluxing material introduced to the fractionator. The fractionated vapors pass overhead through line 23 and valve 24 and are cooled and condensed in coil 25 located in suitable condenser box, and pass through valve 26 and line 21 to be collected in receiver 28, 'wherein the liquefied and gaseous products are separated. Any required portion of the distillate may be withdrawn from receiver 28 through line 29 and valve 38 and directed by meansof pump 3| through line 32 and valve 33 to the top of fractionator 6 as refluxin'g material. The insuiciently converted intermediate products separated out in the fractionator, together with any unvaporized portion of the raw oil introducedthereto, are directed. to the cracking coil, as previously described.

The residual oils resulting from the flash distillation are withdrawn from the vaporizer through line 34 and valve 35 directed by means of pump 36 through line 31 and valve 38 and line 39 to the heating coil 48 disposed within any suitable type of furnace B. Nascent hydrogen may be introduced to the system through line |88, valve |81, and lines |84 and 39 to the heating coil 48, Where the charged materials vare subjected to elevated temperatures and highly superatmospheric pressures. The products from the coil are discharged through line 4| and valve 42 into reaction chamber 43, wherein the hydrogenation reactions initiated in the coil are completed, and the vaporous and non-vaporous products separated. 'I'he liquid products or sludge accumulating in the reaction chamber may be withdrawn through line 44 and valve 45 as the operation progresses or, if the operation is continued until coke or a. substantially dry carbonaceous material is formed in the bottom of reaction chamber, the same may be removed at the end of the operation through manhole 46.

Vaporous products from the reaction chamber are directed to the lower section of fractionator 49.through line 41 and pressure'reducing valve 48. In reducing the pressure from the highly super-atmospheric order maintained on the hydrogenating coil and chamber to that maintained on the succeeding units of the hydrogenating system, a series of automatic pressure-reducing valves may be used in line 41, although only valve 48 is shown on the sdrawing. The vaporous products are fractionated with the assistance of refiuxing material introduced into the top of the fractionator and pass overhead through line 58 and valve 5| and are cooled and condensed in coil 52 located in suitable condenser box, and pass through line 53 and valve 54 to be collected in receiver 55,*wherein the gaseous and liquefied products are separated. Any required portion of thedistillate from receiver 55. may be withdrawn through line 56 and valve 51 and directed by means of pump 58 through line 59 and valve 68 tothe top of fractiohator 49 as reiluxing material. The insufficiently converted intermediate compounds separated out in the' fractionator are withdrawn from the fractionator through line 6| and valve 62 and directed by means of pump 63 through line 39 and valve 64 to heating coil 48.

Any portion of the cracked distillate collected in receiver 28, which is not used as reiiuxlng material in fractionator 6, may be withdrawn through line 65 and valve 66 to be commingled with any portion of the hydrogenated distillate collected in receiver 55 which is not used as refluxing material in fractionator 49, and which is withdrawn from receiver .55 through line 68 and valve 61. 'I'he commingled distillates are directed by means of pump 69 to the heating coil 18, disposed within any suitable type of furnace C,

to be collected in receiver 18, wherein the liqueed and gaseous products are separated. Any required portion of the distillate collected in receiver 18 may be withdrawn through line 19 and valve 88 and directed by means of pump 8| through line 82 and valve 83 to the topl of fractionator 12 as reuxing material. Reflux condensate from vthe fractionator is withdrawn through line 84 and valve 85 anddirected by means of pump 86 through line 81 either through valve 98 and line |I to the heating coil I2, 'or through lines 81 and 88, valve 89 and line 39 to heating coil 48, or partly to both. The reformed gasoline collected in receiver 18 may be withdrawn to storage or use through line |82 and valve |83. f

When desired any portion of the c rackeddis- I tillate collected in receiver 28 may be blended with any portion of the hydrogenated distillate gasoline with an average gravity of 52 A. P. I."

to render it useful and valuable as such for motor i'uel purposes. n

Non-condensable products separated out and collected in receiver are 'withdrawn through valve 93 and line 0d and commingled with noncondensable products separated out and collected in receiver 55, which are withdrawn therefrom through valve 0l and line 08 and also with noncondensable gases separated out and collected in receiver 18, which are withdrawn therefrom through valve i0i and line 04. This mixture of hydrogen-containing gas produced in the various steps of the procm is directed by means of pump 05 through valve we and lines H05 and sa to the heating coil d0 to increase the supply of hydrogenecontaining-gases and to assist the nascent hydrogen in conversion of the dashed residual oil charged to the hydrogenating system. Means are provided for the release of excess pressure on the various systems by withdrawal of excess gases collected in receivers 20. 55 and i0 through pressure control valves M0, H2 and iid, respectively, in lines |00, -ili and H5, respectively.

Conversion temperatures employed in the cracg operation may range from 000 to 950 more or less. Pressur' employed in the cracking zone may vary from atmospheric to super-atmospheric as highas 500 pounds, or more, per square inch. Pressures maintained on the vaporizer are substantially less than those '..employed in the cracg zone and may range from atmospheric to l pounds, or more, per square inch. Equalized or diderential pressures may be employed on the succeeding units or the cracking system.

Conversion temperatures employed in the hy- .drogenating operation may range from 600 to 000 F., more or less. Pressures employed in the hydrogenating zone may vary from substantially atmospheric to highly super-atmospheric of the order oi' 5000 pounds, or more, per square inch. Reduction4 from this high pressure to a much lower pressurev before admitting the hydrogenated vapors to succeeding units of the system may be -accomplished by one. or more pressure reducing valves. Equalized or diilerential pressures may be employed on the remaining elements of the hydrcgenating system.` y

Conversion temperatures employed in the third heating coil'may range from 900 to ,1050cl F., more or less, while the pressures may range from atmospheric to super-atmospheric as high as 500 pounds, or more, per square inch.

As a specic example of the results accomplished by the process covered by this invention, a Mid-Continent crude oil of about 29 A. PQI. gravity was subjected to conversion conditions of appately 900 F. and 200 pounds pressure. This cracking operation resulted in the formation of 'I0 percent of gasoline-within the motor fuel boiling range of approximately 58 A. P. I. gravity and 20 percent of flash residuum of approximately 16 A. P..I. gravity. The gasoline product possessed relatively poor antiknock qualities, which may be in part attributed to the fact that the crude oil contained 15 per cent of straight-run The anti-knock rating of the blended'cracked and straight-run gasoline. was equivalent approximately to a blend oi 64 per cent iso-octane and 36 per cent of normal heptane or a benzol equivalent of 50 per cent. The residual oil from the cracking operation, subjected to a temperature .of 850 F. in the second heating coil in the presence of a suiilcient supply of nascent hydrogen` and noncondensable gases produced in the various steps of the process, and under pressure of 2000 pounds per square inch, yielded a product also having a low anti-knock quality. The reconversion of the flashed residuum from the cracking operation resulted in the formation of 18 per cent of gasoline, based on the crude oil, within the motor fuel boiling range, having an anti-knock rating approximately equivalent to that of a blend of 76 per cent oi iso-octane and 24 per cent normal heptane, or an approximate benzol equivalency of 62 per cent. All of the cracked distillatewas mixed with all of the hydrogenated distillate and subjected in the reforming step of the process to a temperature of 930 F. and 500 pounds pressure, which operation resuted in the formation of a reformed gasoline of considerably improved antiknocl: quality, gum content and' stability. The

reformed gasoline had an anti-knock rating approximately equivalent to that` of a blend of 8i l per cent of iso-octane and 16 per cent normal ethane, etc. The non-condensable gases from the hydrogenating operation showed approximately 25% of hydrogen, which might be expected from.

the fact that the hydrogenating reaction takes piace inthe presence of excess amount of hydrogen. The re-lormirig operatioi of the process resulted in the production of a gas containing approximately 3% hydrogen. This amount of hydrogen produced in the three steps of the process, although in the molecular state, is a valuable adjunct in assisting the hydrogenating reaction and assuring a maximum saturation with hydrogen.

AThis feature becomes apparent to one skilled in the art -or with the point of view of the physical chemist from a consideration of mass reactions.

A proof of the value to the process o f this feature or recirculating the non-condensable gases produced in the cracg, hydrogenating and reforming operations for use in assisting the hydrogenating operation was had, whemduring the operation of the process, all thenon-condensable gases produced were liberated from the system excepting an amount necessary to maintain desirable pressures. As a result oi this change in operation it was. found that the yield of gasoline resulting from the hydrogenating of the flashed residuurn was decreased to 15% based on the crude oil' charged to the process, and that the same product showed a lower antiknock rating,

approximately 69 octane number or a benzol equivalency of 55. Furthermore, it was found that thisk gasoline contained more gum-forming and sulfur compounds. which could easily be inferred from the fact that hydrogen, which-has a pronounced 4de- :n .1 ing and de-sulfurizing iny iluence,wasnot in such copious supply as in the operation of the process the hydrogenated gasoline product has no sour odor.

Naturally enough the reformed gasoline obtained from mixing and recracking this hydrogenated gasoline of inferior quality with the cracked gasoline would suifer an appreciable, though not necessarily corresponding, decrease in anti-knock properties and increase in gum and sulfur contents. This increase in the amount of gum-forming and sulfur constituents and decrease in anti-knock value when the non-condensable gases of the process were not being used to assist the hydrogenating operation is evidence of the benecial effect of the utilizing of such an amount of molecular hydrogen available under the preferred operating conditions of the process. y

The relatively low anti-knock rating oi' the cracked gasoline produced in the rst stage of this process rendered that product by itself of little value as a motor fuel in the present market of premium gasolines. 0n the other hand the anti-knock rating of the hydrogenated gasoline approximately equivalent to that of ethyl standard gave that gasoline a qualified value among the premium motor fuels of the day. Howev'en'it was found that by proportioning the amounts of Acracked gasoline and hydrogenated gasoline to form a uniform mixture which was not subjected to the reforming step of the process, a product was obtained that had considerably improved anti-knock properties over the cracked gasoline and was generally useable as a motor fuel. As a specific example of the improvements in antiknock rating that may be obtained by blendingalone, without employing the reforming step of the process, it was found that a blend of equal proportions of the cracked gasoline in the example previously specied having an anti-knock rating of 64% iso-octane and the hydrogenated gasoline of the same example having an antiknock rating of 76% iso-octane had an antiknock rating approximately equal to that of a blend of 72% iso-octane and 28% normal heptane or a benzol equivalency of approximately 58% benzol. Thus by blending the cracked and hydrogenated gasolines without resorting to the reforming step of the process larger quantities of a valuable commercial grade of motor fuel may be economically obtained.

I claim as my invention:

1. In processes for cracking hydrocarbon oil of the character in which the oil is subjected to4 cracking conditions of temperature and pressure, thence separated into vapors and residue in a. separating zone, the vapors subjected to fractionation to condense intermediate products heavier than gasoline and the lighter vapors iinally condensed to form gasoline-containing i distillate, the improvement which comprises sub-- jecting the gasoline-containing distillate to temperature conditions adequate to reform and improve the antiknock characteristics of the gasoline components thereof, recovering the reformed distillate and gases resulting from the reforming operation and subjecting such gases and the residue of the cracking process to hydrogenating conditions of temperature and pressure in an independent hydrogenating zone and recovering distillate from the hydrogenation of the residue and combining the same with the distillate from the cracking operation to be concurrently reformed therewith.

2. A hydrocarbon oil conversion process which comprises subjecting-the oil to cracking condi--` tions of temperature and pressure in a cracking zone and separating the same into vapors and residue, dephlegmating the vaporsy to condense fractions thereof heavier than gasoline, finally condensing the dephlegmated vapors and separating the resultant gasoline distillate from the incondensable gases, passing such gases and said residue to a; hydrogenating zone maintained under hydrogenating conditions of temperature and pressure and hydrogenating the residue therein, separating a gasoline-containing distillate from the thus treated residue and combining portionsthereof with portions of the first-mentioned distillate, passing the resultant mixture through an independent heating zone and heating the same therein sufficiently to substantially increase the anti-knock properties of the gasoline content of the mixture, recovering the gasoline thus retreated, and supplying incondensable gases formedby the last-named heating step to the hydrogenating zone.

3. A conversion process which comprises subjecting hydrocarbon oil to cracking temperature under pressure and separating lthe same into vapors and residue, fractionating the vapors and separating therefrom a light fraction containing low anti-knock gasoline hydrocarbons, subjecting said residue to hydrogenation to produce lower boiling products therefrom, combining lower boiling products thus formed with said light fraction, subjecting the resultant mixture to cracking conditions adequate to enhance the antiknock value of its gasoline content, separating resultant anti-knock gasoline from incondensable gases and supplying at least a portion'of the lat-I ter Ito the hydrogenating step to furnish hydrogen for the hydrogenation of said residue.

4. A conversion process which comprises subjecting heavy hydrocarbon oil to relatively mild cracking, thereby forming unvaporized residue and'gasoline fractions of low anti-knock value, reforming said gasoline fractions to enhance their anti-knock value, by a dehydrogenating conversion treatment at higher temperature than that at which said heavy oil is cracked, thereby liberating hydrogen from the gasoline fractions, combining resultant hydrogen-containing gas from the reforming operation with unvaporized residue from said relatively mild cracking and subjecting the combined materials, independently of said heavy oil, to hydrogenating conditions adequate to produce lower boiling products from the residue.

5. The process as defined in claim 4 further characterized in that low anti-knock gasoline fractions produced by the hydrogenating operation are reformed together with said gasoline fractions of the relatively mild cracking.

J. WARREN McCAFFREY. 

